I've been following this thread for years and years but at unfortunately it makes think of a Bjork song more and more often.... "it's oh so quiet"From your youtube channel I notice you are still making nice progress but would it be possible to do one of your classic updates, one with all the nice little details and so on, just for old time sake

So I have what may be one of the more unusual questions that have been asked on this thread. I've just published a book entitled Lunar Dance. It's a science fiction thriller that's set amid the commercial launch industry. Many of the key characters work for a small aerospace firm called Roadrunner Rockets, which is the offshoot of a computer gaming company based outside of Dallas. The innovative technology they've developed becomes the key enabler that leads to the greatest adventure in history. I'd love to send a copy to the fine folks at Armadillo Aerospace, because I think you'd get a kick out of it. Should I just mail a copy to the contact address listed on your website? Or would there be a better way to put a copy in Mr. Carmack's hands?

_________________Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage. Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines and stages at the same time, and the result will automatically be SSTO.Blog: http://exoscientist.blogspot.com

Having read the reports of STIG-B I, II, and III, I have the following question:

Why is GPS considered required for flight? Could you not use the IMU for navigation and anticipation of license limits (like groundspeed limits etc), use the GPS signals that you do get successfully to update the IMU's position and velocity, and thus have a hybrid system robust to GPS dropouts, yet still capable of GPS-level accuracy when available?

Having read the reports of STIG-B I, II, and III, I have the following question:

Why is GPS considered required for flight? Could you not use the IMU for navigation and anticipation of license limits (like groundspeed limits etc), use the GPS signals that you do get successfully to update the IMU's position and velocity, and thus have a hybrid system robust to GPS dropouts, yet still capable of GPS-level accuracy when available?

thanks,

Steven Kasow

As best as I can tell from reading the reports for STIG-B II and III, that is exactly what they are trying to do. That they are expecting to be able to handle a specific amount of loss of accuracy as well as complete single loss, but ultimately they must have limits on what is acceptable. They could increase that limit, but at some point making the limit so large effectively says "we don't need GPS for flight control". It looks like their limit is currently 10 seconds of complete loss of signal before they pass an abort threshold.

The question them becomes "Is the threshold too short". Meaning is it common to have a total loss of single for longer than 10 seconds. I think that the likely obvious answer to that is that a loss of that long should not be considered normal or expected. And, it sounds like they are on the trail of the problem anyhow (aero/engine noise and/or APRS interference).

My totally newbie question is like yours (which I am sure there is a good answer for)...

"I can understand the benefit of having GPS, but why not rely 100% upon IMU for flight control."

I suspect the answer is that you could do it all via IMU (as was done decades ago), but that they really want/need the GPS accuracy. I also wonder if having a flight control system that uses both IMU and GPS (and not just one) also helps keep the worse case scenario (Ec value) low when they calculate those types of things. I also assume the same GPS system is used to feed info to the Wamore recovery system? And GPS accuracy probably will matter for future paying customers as well.

Ultimately it sounds like GPS issue is solvable anyhow. Its just unfortunate that it is such an expensive (loss of vehicle) learning curve right now.

Well, that was due to a freak hangup in the parachute system it seems, not due to the GPS. I don't see anything they could have done to prevent it, even extensive simulation seems unlikely to have caught that possibility. I presume that the parachute system is bog standard, and that they didn't unnecessarily try to reinvent the wheel. But we've been promised a write-up, so details will emerge on that one.

Armadillo themselves have commented before on how difficult it is to get a good GPS trace on a high-altitude rocket, in the discussion surrounding the Carmack Prize. It looks like they were right, and hopefully they're on the right track to solving this issue.

I've looked a bit into the sounding rocket market, and it seems that STIG B is not that impressive as sounding rockets go. (Combinations of) Terrier, Malemute, Black Brant, other existing systems go significantly higher (up to 1500km!) and provide much more microgravity time. However, these are all multi-stage, single-use, solid propellant rocket systems, as opposed to Armadillo's reusable liquid propellant rocket. I can't find prices on any of these, but it seems logical that a reusable rocket can be cheaper per flight than an expendable one, even if those solid rocket motors are likely to be quite a bit cheaper to manufacture than AAs liquid engines and fuel tanks. So I can see them being competitive in that respect.

Also, these other rockets land wherever they land, and you're quite likely to lose your payload on the higher altitude flights, as they go hundreds of miles downrange. So it seems quite possible that AA have found a market niche for cheap flights that reliably return the payload (saving money again), with a usable if not overly impressive amount of microgravity time. Location may also help, since those other sounding rockets seem to be launched from the polar regions, while there are quite a few universities with space-related courses in the southern US. If you want to get an actual payload up on an education budget, it's starting to look quite attractive.

Let's hope they can figure out an easier manufacturing method, make a couple of vehicles, and grow this into a successful business.

_________________Say, can you feel the thunder in the air? Just like the moment ’fore it hits – then it’s everywhereWhat is this spell we’re under, do you care? The might to rise above it is now within your sphereMachinae Supremacy – Sid Icarus

It has been a long time since I even looked at the forum here. I left Armadillo back around Sept 2012. It just wasn't working out for me there as things had changed from the original design I had joined up with. The business had become more of a traditional environment that management made the decisions, and everyone did their own fields (and what management wanted done). There was a lot of other stuff besides that, but I don't feel a need to bash AA. The turkey is cooked.I have gone back to welding and teaching. Its closer, more profitable, and less heartbreaking.I will answer any and all questions that I can, but please keep it simple. My free time is pretty tight. Also, I am not a rocket scientist, I am a welder/fabricator, so don't expect great answers regarding rocket science.